The present invention is generally related to controlling the speed of motor vehicles. More particularly, the present invention is related to controlling the speed of vehicles with limited stability, including motorized scooters for persons of limited mobility.
A scooter is a motorized, usually battery electric, vehicle, typically for a person who is able to walk but is not able to walk long distances. For psychological reasons, scooters are designed to look more like a motor-scooter than a wheelchair. It must be possible for the scooter to be driven indoors, at least to some extent, so the scooter typically has a fairly small floorplan area. In order that a user of limited agility may easily mount and dismount, the user""s seat is set fairly high. These and other constraints necessarily require some compromise with the handling of the scooter, and such scooters are not always very stable. Consequently, at present such scooters are sometimes limited to speeds within the range of about 5 to 6 mph. However, this maximum speed limits the usefulness of the scooter. For example, a journey of a few miles from the user""s home to a shopping area can become oppressively time consuming.
An all-terrain vehicle (ATV) is a small, one-person motor vehicle designed to be driven over rough ground. Because of the need for high ground-clearance, an ATV may have a high center of gravity. Because it is driven for fun, the users tend to desire as high a maximum speed as is commensurate with safety. However, a speed that is attractive to the user when traveling in a straight line on generally level ground may be higher than is prudent on curves or on sloping ground. Conversely, if the maximum speed is governed to a value that is suitable for curves and slopes, the user may find the vehicle unduly tame when traveling in a straight line.
The present invention is directed to a motorized vehicle that can travel substantial distances more quickly, without compromising the stability of the vehicle.
One aspect of the present invention provides a motorized vehicle that has a propulsion system switchable between two modes, one of which allows a higher maximum speed than the other. The mode is selected by a user-operated switch so constructed that the high-speed mode is selected only while the user continues to operate the switch. Sensors are also provided to detect maneuvers or conditions for which stability may be a consideration in determining the maximum speed of the vehicle. In response to the output of such sensors the low-speed mode is automatically selected. Maneuvers sensed may include sharp turns, and conditions sensed may include steep slopes, up, down, or sideways.